The invention relates to a method for bringing people in life boats in the sea aboard a support vessel.
The invention also relates to a support vessel for launching and recovery of rescue crafts and life boats.
Some marine operations and installations are supported by a support vessel. The support vessel may provide fuel supply, radio communication, operational control and helicopter landing and fuelling facilities.
A particular purpose of a support vessel is to rescue people from life boats. In calm weather this is straightforward, and can be done by ladders, or by baskets hanging from a crane on the support vessel. In bad weather, however, both the use of ladders and baskets are endangered by the waves and the wind, and bringing people from a life boat to a support vessel is a risky operation.
Another purpose of a support vessel is rescue of personnel from the sea. For this purpose the support vessel may carry one or more rescue craft, with room for e.g. 20 persons. Rescue crafts are conventionally carried in davits or cribs, and are launched and recovered by cranes on the support vessel. In calm weather both launching and recovery of a rescue craft by a crane is straightforward. In bad weather, however, these lifting operations are risky, and can hardly be carried out.
A particular use of a support vessel is as a stand by vessel for one ore more oil platforms at an offshore field. North Sea offshore platforms normally have free fall lifeboats, i.e. closed life boats which are located on the platform, typically 30 meters above the sea surface. In an emergency situation these life boats are filled with personnel, and launched by a free fall. Free fall life boats have a small engine which can bring the life boat away from the oil platform. A free fall life boat is, however, both due to small engine power and small internal space, not suitable for long time use.
In bad weather significant wave height, i.e. the average height of the highest {fraction (1/3 )} of the waves in a certain time period, e.g. one hour, can be 10 meters in the North Sea. Bringing people from a life boat to a support vessel is then not straight-forward, as discussed above. One way of transferring people is to use a helicopter, lifting one person at a time. An oil platform may have a crew of 100-200 persons, seated in e.g. four life boats, and thus bringing all people in safety by a single or maybe two helicopters is slow. Further, in addition to being time consuming, helicopter lifting and transport are risky in bad weather. Another way of rescuing the people is to tow the life boats ashore, which is also time consuming in the North Sea, as the distance to shore my be e.g. 200 km,
The object of the invention is thus to provide a method for bringing people in life boats in the sea aboard a support vessel, which method shall be quicker and safer in bad weather than conventional methods.
The object is further to provide a support vessel for launching and recovery of rescue crafts and life boats, which launching and recovery shall be possible in bad weather.
The objects are achieved by a method and a support vessel as mentioned in the preamble, which are characterised by the features of the claims.
Thus the invention relates to a method for bringing people in life boats in the sea aboard a support vessel, in which a rescue craft is launched from a ramp in the stern of the support vessel, the rescue craft carrying a rope from a winch in front of the ramp, the rope is attached to a life boat in the sea, the life boat is hauled onto the ramp by the winch, and the life boat is emptied.
In a preferred embodiment, when bringing people from more than one life boat aboard the support vessel, the first, empty life boat is marked and returned to the sea. The rope from the winch is released from the empty life boat and picked up by the rescue craft, and attached to a second life boat in the sea. The second life boat is hauled onto the ramp, and emptied. The second, empty life boat is also marked, and returned to the sea, and in this way all life boats are brought onto the ramp and emptied.
The people in the life boats are thus brought aboard the support vessel in a quicker way than in conventional methods. Further this way of bringing people aboard the support vessel does not involve the use of a crane, and can be carried out in bad weather.
The support vessel for launching and recovery of rescue crafts and life boats according to the invention comprises a stern ramp for launching and entering of rescue crafts and life boats and a winch for hauling the rescue crafts and life boats onto the ramp.
Preferably the ramp slopes astern towards the sea, and has a V-shape for supporting the rescue crafts and the life boats. Further the ramp is preferably perforated, to dampen waves of the sea The ramp may be supported by vertical, perforated baffles extending transverse to the support vessel""s longitudinal direction, to dampen motion of the sea underneath the ramp.
The support vessel is preferably provided with a rounded fender portion on each side of the ramp, besides or astern the ramp, to facilitate the entering of the rescue crafts and the life boats.
Preferably the ramp forms a part of an enclosed reception area with a closable entrance hatch for the launching and entering of the rescue crafts and life boats.
The support vessel preferably comprises at least one hatch cover which in the front is hinged to the support vessel underneath the entrance hatch, which hatch cover in a raised position closes at least a part of the entrance hatch and in a lowered position forms an extension of the ramp in the sea.
The rescue craft is preferably kept in place on the ramp by at least one locking arm on each side of the ramp. For adaption to different life boat shapes, the locking arm may be hinged in a lower end and in an upper movable end having a convex portion pointing towards the rescue craft or life boat.
The support vessel is thus feasible for launching and recovery of rescue crafts and life boats without the use of a crane, and the launching and recovery can be carried out in bad weather.
Other objects, embodiments and advantages of the invention will appear from the detailed part of the description.